different 5k distributor p/ns?

[Andrew Sitzer]

Hey all, does anyone know if there is a difference between the
0237030009 and the 0237030021?  I found that the 0009 is for 8/84 through
7/86 and the 0021 is for 8/86 to 3/87...  But is there any actual
difference?

My 86 5ks currently has a 0005 in it (which is for 1984s) and my mechanic
highly recommends I replace t with the correct one.  He told me I need a
0009 -- but I want to be positive this time :)

-Andrew S.